Renal Denervation: Just How Big Is The Bandwagon?

In short

There are plenty of parallels in the history of medical device development, but there’s no doubting the fact that this particular bandwagon is gathering pace at a rate not seen since the early days of coronary angioplasy, balloons, stents and all that. And it’s  easy to see why, because renal denervation, despite being a recently developed therapy, does seem to be generating a fistful of good results, demonstrating immediate and sustained blood pressure reduction in patient hitherto resistant to pretty much any other form of anti-hypertensive therapy.

So in true Rumsfeldian fashion let’s ponder what are the knowns, unknowns and known unknowns about the market as it stands.

Who’s at the party?

What we do know is that most of the big boys are in it, and at some cost, which suggests they’ve done the maths and voted in favour. Medtronic’s Symplicity™ is perhaps the best characterised device, having been acquired as part of the companies $800M takeover of Ardian Systems in 2010 and with arguably the biggest data set behind it. Consequently however there is speculation that the company considers it’s first-to-market status carried with it first-to-obsolescence status and that it is either developing or seeking to acquire a next generation offering.

Elsewhere, most recently Covidien dived in with its acquisition of Maya Medical May of this year. St.Jude’s EnligHTN™ was only CE marked in May of this year, but the company is claiming greater performance in blood pressure reduction than its rivals. Of the smaller participants, Vessix’s clever V2 System, with RF electrodes built into the outside of a balloon, was CE marked in early May and claims its USP is a very short energy delivery time of 30 seconds. ReCor’s Paradise™ was CE marked in February 2012 and is the only device based on ultrasound energy delivery, which it claims to be more efficient than its RF-based rivals.  Boston Scientific is also up to its neck in the technology with its RDN system slated for CE mark approval some time in 2013.

Simple procedure

Also on the list of things we know is that whichever of the products one uses, it’s a pretty straightforward procedure involving pretty much conventional insertion of one of the aforementioned devices into the renal artery, pressing fire and in so doing zapping some of the sympathetic nervous system associated with the renal arteries which, by the miracle of the body’s feedback system controls blood pressure. In other words, by ablating overactive neurons in this area, blood pressure can be reduced. According to a new paper published in May’s Journal of the American Society of Nephrology, kidney function is not impaired and may itself be improved by the procedure.

As we said earlier. with the exception of ReCor’s Paradise ultrasound-based device, all other systems employ radiofrequency energy in one way or another, the idea being that this energy destroys cells local to it by a process of ohmic resistance, well characterised in other areas of surgery including cardiac ablation treatment for arrhythmia.

Market size?

What we don’t know at the moment is the absolute size of the market opportunity. All the players quote their own estimates of the size of the target patient group and these are undeniably huge. The American Heart Association reckons that by reducing blood pressure in hypertensive patients by 5mmHg, their stroke risk could be reduced by 14%, and furthermore that high blood pressure is the leading cause of death on a global basis, all of which makes the rush to a therapeutic solution understandable.

The common ground between the various commentators seems to be that about a third of the developed world’s adult population is hypertensive, with a third of these undergoing some form of antihypertensive therapy, usually drugs, a third of whom are so-called unresponsive, so theoretically being potential candidates for renal denervation therapy. Vessix Medical puts a number on it, estimating a current target audience of 12 million people and an ultimate market, subject no doubt to gaining US FDA approval, worth in the order of $30Billion. Others are a tad more conservative, but even if you miss a zero off, (as most commentators do by the way) it’s still a significant number.

US regulatory status

Speaking of FDA approval, the known unknown is FDA’s attitude towards Renal Denervation. None of the products are FDA approved, yet all are in pursuit. Medtronic is at the front of the race, having gained IDE approval in July 2011 for its HTN-Symplicity III trial, with an expectation that the company may gain approval by 2014, but that’s more of an estimate than a certainty, so for the time being it’s a technology to which US patients don’t have access other than through a study.

As a footnote, if you’re a European you might like to read this heart-related blog, written by (presumably) a US cardiologist last month. Then again you might not, because he’s somewhat damning of the current evidence base and uses the term “experimental” to describe the technology. No doubt that’s a comment that’s intended to head off all his enquiring patients at the pass, but we think he’s going to have to get used to it for a while, because Renal Denervation is, in our opinion, going to be big… nobody really knows how big, but big.

Source: medlatest staff